Velocity V of electromagnetic waves in concrete is obtained from the following formula:
（ｍ／ｓ）
ε
Ｃ
Ｖ＝
ｒ
C: Velocity of electromagnetic waves in vacuum (in air) (3
×
10
8
m/s)
: Relative dielectric constant of concrete (6 to 11 in the example)
Distance D to the reflecting object is obtained from the following formula:
（ｍ）
ＶＴ
２
１
Ｄ＝
5.2
Applicable Conditions
(1)
Applicable measuring conditions
(Waves reflected by objects to be scan tested in reinforced concrete structures must be received
adequately, so the applicable measuring conditions vary slightly depending on the on-site condition.)
○
Scan test depth (covering depth) within 0.5 ~ 30 cm (case where relative permittivity of concrete
is 6.2 and the diameter of the rebar is at least 6mm)
○
Objects to be probed that are at a depth of less than 75 mm have an interval spacing of at least
75 mm and where the depth of the object to be probed is greater than 75 mm, the interval
spacing of the objects is more than the depth
○
Quality of concrete: Uniform
○
Direction of reinforcing steel: Orthogonal to the Handy Search's traveling direction
(2)
Inapplicable measuring conditions
○
Scanning of reinforcing steel or the like in concrete whose surface contains objects such as
metal that reflect radio waves
○
Presence of reinforcing steel bars that are parallel to the Handy Search's traveling direction
○
Concrete that has a narrow (pitch) arrangement for the interval of rebar in the horizontal
direction
(Target: depth less than 75 mm
→
interval between rebar, less than 75 mm
Depth of greater than 75 mm
→
interval of rebar less than depth)
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Summary of Contents for Handy Search NJJ-95B
Page 1: ...Handy Search Instruction Manual...
Page 8: ...Appearance of the NJJ 95B vii...
Page 21: ...Rear view Units in trigonometry mm 9...
Page 24: ...8 14 15 Figure 2 2 Side View 16 17 14 18 Figure 2 3 Rear View 12...
Page 73: ...Display of thumbnails Figure 3 17 CF Control Screen 61...
Page 83: ...B Terminals ACharge confirmation mark Figure 3 22 Battery Pack 71...
Page 85: ...Shutter Charge lamp Figure 3 23 Battery Charger 73...
Page 96: ...Concrete Rebar D 75mm L 75mm D 75mm Difficult to implement 84...
Page 103: ...Dimensions Weight About 149 W x 147 H x 216 D mm Approximately 1 1kg 91...
